U.S. patent application number 11/417257 was filed with the patent office on 2006-12-07 for retrievable downhole tool and running tool.
Invention is credited to David John Copeland Manson.
Application Number | 20060272828 11/417257 |
Document ID | / |
Family ID | 34575075 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272828 |
Kind Code |
A1 |
Manson; David John
Copeland |
December 7, 2006 |
Retrievable downhole tool and running tool
Abstract
A downhole tool and a running tool are described, each being
retrievably settable within a suitably sized cased well bore
without the need for any interaction between the downhole tool or
the running tool and any restrictions or recesses in the well bore
to land, anchor or retrieve either tool. The downhole tool has a
mandrel, an anchoring means mounted on the mandrel and controllably
reconfigurable from a retracted configuration to permit movement of
the downhole tool through the well bore to a radially expanded
configuration for releasably engaging the cased well bore. The
downhole tool anchoring means is reconfigured using a ratchet that
resists movement of the tool anchoring means from the expanded
configuration back to the retracted configuration until a release
mechanism is released to allow retraction of the downhole tool
anchoring means and retrieval of the downhole tool from the well
bore.
Inventors: |
Manson; David John Copeland;
(South Lake, AU) |
Correspondence
Address: |
EDELL, SHAPIRO & FINNAN, LLC
1901 RESEARCH BOULEVARD
SUITE 400
ROCKVILLE
MD
20850
US
|
Family ID: |
34575075 |
Appl. No.: |
11/417257 |
Filed: |
May 4, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/AU04/01527 |
Nov 5, 2004 |
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11417257 |
May 4, 2006 |
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Current U.S.
Class: |
166/387 ;
166/138 |
Current CPC
Class: |
E21B 23/006 20130101;
E21B 33/129 20130101; E21B 23/06 20130101 |
Class at
Publication: |
166/387 ;
166/138 |
International
Class: |
E21B 33/129 20060101
E21B033/129 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2003 |
AU |
2003906144 |
Oct 15, 2004 |
AU |
2004905951 |
Claims
1. downhole tool retrievably settable within a suitably sized cased
well bore, the downhole tool comprising: a mandrel; a downhole tool
anchoring means mounted on the mandrel and reconfigurable from a
retracted configuration to permit movement of the downhole tool
through the well bore to a radially expanded configuration for
releasably engaging the cased well bore, the downhole tool
anchoring means being biased towards the retracted configuration; a
downhole tool setting means for resisting movement of the tool
anchoring means from the expanded configuration back to the
retracted configuration until a release mechanism is released to
allow retraction of the downhole tool anchoring means and retrieval
of the downhole tool from the well bore; and, one or more locking
means for locking the downhole tool anchoring means in the
retracted configuration after the release mechanism has been
released.
2. The downhole tool of claim 1 wherein the downhole anchoring
means is reconfigured from the retracted configuration to the
radially expanded configuration upon application of an axial
force.
3. The downhole tool of claim 1 wherein the downhole anchoring
means is a set of bidirectional slips.
4. The downhole tool of claim 1 wherein the downhole tool setting
means is a ratchet.
5. The downhole tool of claim 1 wherein the release means is
arranged for engagement with a fishing tool and operable thereby to
permit release of the downhole tool setting means allowing the
downhole tool anchoring means to retract into the retracted
configuration for retrieval of the downhole tool.
6. The downhole tool of claim 1 further comprising a sealing means
for providing a fluid seal between the downhole tool and the well
bore such that the downhole tool operates as a plug.
7. The downhole tool of claim 6 wherein the sealing means is
controllably reconfigurable from a retracted configuration to
permit movement of the downhole tool through a well bore and a
radially expanded configuration for sealing engagement with the
bore wall.
8. The downhole tool of claim 7 wherein the sealing means is
expanded into sealing engagement with the bore wall by applying a
repeated compressive force to the sealing means after the downhole
tool anchoring means has been expanded into engagement with the
well bore.
9. The downhole tool of claim 1 wherein the downhole tool anchoring
means are positioned below the downhole tool sealing means.
10. The downhole tool of claim 1 further comprising a pressure
equalisation means for equalising any pressure differential that
may exist across the downhole tool prior to retrieval.
11. The downhole tool of claim 1 further comprising a downhole tool
setting release means releasable from a locked configuration in
which expansion of the downhole tool sealing and/or anchoring means
is prevented to a released configuration in which expansion of the
downhole tool sealing and/or anchoring means is permitted.
12. The downhole tool of claim 10 wherein the downhole tool setting
release means is in the form of one or more shear pins, shear
screws or snap rings.
13. The downhole tool of claim 8, in combination with a running
tool for landing and reconfiguring the tool in the well, the
downhole tool being releasably coupled to the running tool.
14. The downhole tool of claim 1 further comprising a measuring
device for monitoring one or more well parameters.
15. The downhole tool of claim 14 wherein the measuring device is
suspended from the downhole tool and the mandrel of the downhole
tool is hollow to permit the flow of fluids therethrough.
16. A running tool for landing and setting a retrievable downhole
tool at any location in a well bore, the running tool comprising:
an inner rod; a running tool anchoring means mounted on the inner
rod and controllably reconfigurable between a retracted
configuration to permit movement of the tool through the well bore
and a radially extended configuration for locking engagement of the
running tool with the bore wall; a running tool actuating assembly
for effecting reciprocal movement of the reconfiguring the running
tool anchoring means to and from the retracted and expanded
configurations without interacting with any restrictions or
recesses within the well bore; the tool actuating assembly being
moveable from a first configuration in which the tool anchoring
means is retracted and a second configuration in which the tool
anchoring means is expanded in response to the application of an
axial force; and, a resistance means for frictionally engaging the
bore wall with sufficient gripping force so as to hold the position
of the running tool relative to the well bore during movement of
the running tool actuating assembly to and from the first and
second configuration upon application of the axial force.
17. The running tool of claim 16 wherein the running tool anchoring
means is in the form of a set of slips cooperating with at lease
one expansion cone, each slips provided with a plurality of teeth
directed to resist downward movement of the running tool when the
running tool anchoring means is in the expanded configuration.
18. The running tool of claim 16 wherein the resistance means has a
fixed end and an axially slidable end to accommodate movement of
the running tool past any restrictions in the well bore during
setting and/or retrieval of the running tool.
19. The running tool of claim 16 wherein the resistance means is
one ore more bow springs.
20. The running tool of claim 16 wherein the running tool anchoring
means is biased towards the retracted configuration.
21. The running tool of claim 16 wherein the running tool actuating
assembly is a J-slot mechanism comprising an actuating pin
receivable in a J-slot profile, the J-slot profile having one ore
more short legs and one ore more long legs, the actuating pin being
constrained to move between a short leg and a long leg upon
application of an axial pulling force to the tool actuating
assembly, whereby when the actuating pin is located in one of the
short legs the tool anchoring assembly is in the first
configuration and when the actuating pin is located in one of the
long legs the tool anchoring assembly is in the second
configuration.
22. The running tool of claim 16 wherein the running tool actuating
assembly comprises a J-slot mechanism comprising an actuating pin
receivable in a J-slot profile, the J-slot profile having one or
more short legs and one or more long legs, the actuating pin being
constrained to move between a long leg and a short leg upon
application of an axial pushing force to the tool actuating
assembly, whereby when the actuating pin is located in one of the
long legs the tool anchoring assembly is in the first configuration
and when the actuating pin is located in one of the short legs the
tool anchoring assembly is in the second configuration.
23. A downhole tool/running tool system for retrievably setting the
downhole tool at any location within a well bore, the system
comprising: a running tool comprising an inner rod, a running tool
anchoring means mounted on the inner rod and controllably
reconfigurable between a retracted configuration to permit movement
of the tool through the well bore and a radially extended
configuration for locking engagement of the running tool with the
bore wall, a running tool actuating assembly for effecting
reciprocal movement of the reconfiguring the running tool anchoring
means to and from the retracted and expanded configurations without
interacting with any restrictions or recesses within the well bore,
the tool actuating assembly being moveable from a first
configuration in which the tool anchoring means is retracted and a
second configuration in which the tool anchoring means is expanded
in response to the application of an axial force, and, a resistance
means for frictionally engaging the bore wall with sufficient
gripping force so as to hold the position of the running tool
relative to the well bore during movement of the running tool
actuating assembly to and from the first and second configuration
upon application of the axial force; a downhole tool comprising a
mandrel, a downhole tool anchoring means mounted on the mandrel and
reconfigurable from a retracted configuration to permit movement of
the downhole tool through the well bore to a radially expanded
configuration for releasably engaging the cased well bore, the
downhole tool anchoring means being biased towards the retracted
configuration, and, a downhole tool setting means for resisting
movement of the tool anchoring means from the expanded
configuration back to the retracted configuration until a release
mechanism is released to allow retraction of the downhole tool
anchoring means and retrieval of the downhole tool from the well
bore; and, means for releasably coupling the downhole tool with the
running tool, said means facilitating transfer of axial loads
between the running tool and downhole tool during landing and
setting of the downhole tool in the well bore and arranged to
release the running tool from the downhole tool upon application of
an upward jarring force.
24. The downhole tool/running tool system of claim 23 wherein the
means for releasably coupling the downhole tool with the running
tool includes one or more load transfer keys axially moveable along
a keyway in response to the application of an axial force whereby
an axial force applied to the running tool is transmitted to the
downhole tool.
25. The downhole tool/running tool system of claim 23 wherein the
downhole tool further comprises a downhole tool sealing means
mounted on the mandrel and moveable from a retracted configuration
to permit movement of the downhole tool through a well bore and a
radially expanded configuration for sealing engagement with the
bore wall.
26. The downhole tool/running tool system of claim 23 further
comprising one or more seals in combination with the sealing means
for ensuring pressure integrity across the downhole tool sealing
means when the downhole tool sealing means is in the radially
expanded configuration.
27. The downhole tool/running tool system of claim 23 further
comprising a measuring device for monitoring one or more well
parameters.
28. A method of setting a downhole tool in a bore, the method
comprising: a) coupling the downhole tool of claim 1 with a running
tool so as to form a running tool/downhole tool assembly, wherein
the running tool comprises: an inner rod; a running tool anchoring
means mounted on the inner rod and controllably reconfigurable
between a retracted configuration to permit movement of the tool
through the well bore and a radially extended configuration for
locking engagement of the running tool with the bore wall; a
running tool actuating assembly for effecting reciprocal movement
of the reconfiguring the running tool anchoring means to and from
the retracted and expanded configurations without interacting with
any restrictions or recesses within the well bore: the tool
actuating assembly being moveable from a first configuration in
which the tool anchoring means is retracted and a second
configuration in which the tool anchoring means is expanded in
response to the application of an axial force; and, a resistance
means for frictionally engaging the bore wall with sufficient
gripping force so as to hold the position of the running tool
relative to the well bore during movement of the running tool
actuating assembly to and from the first and second configuration
upon application of the axial force; b) running the running
tool/downhole tool assembly into the bore of a well to any desired
location within the well bore, the running tool anchoring means and
the downhole tool anchoring means being in their respective
retracted configurations; c) applying an axial force in a first
direction to the running tool so as to reconfigure the running tool
anchoring assembly into the expanded configuration; d) thereafter
applying an axial force in a second direction to reconfigure the
downhole tool anchoring assembly into the expanded configuration in
engagement with the bore wall so as to set the position of the
downhole tool within the well bore; and e) thereafter releasing the
running tool from the downhole tool for retrieval of the running
tool from the well bore.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT/AU02004/001527,
filed Nov. 5, 2004, and titled "A Retrievable Downhole Tool and
Running Tool," which claims priority to Australian Application No.
AU 2003906144, filed on Nov. 7, 2003, and to Australian Application
No. AU 2004905951, filed on Oct. 15, 2004, the entire contents of
which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a well tool that is
settable at any location within the bore of a well and can be
subsequently retrieved to the surface. The present invention
further relates to a running tool for running and setting a
retrievable well tool.
[0003] The running tool and/or well tool of the present invention
may be used in any type of cased well, including sub-sea wells,
platform wells and land wells. The present invention relates
particularly, though not exclusively to wells used for oil and/or
gas production, but is also applicable to gas and/or water
injection wells.
BACKGROUND OF THE INVENTION
[0004] It is common practice to run, land, set and retrieve
downhole tools within the borehole of a well to perform various
functions including sealing the bore of the well or for carrying a
measuring device for monitoring parameters such as pressure or
temperature within the well. Typically the borehole of a well is
cased using drillpipe, casing or tubing string which is designed in
such as way as to provide predetermined locations for landing and
setting such downhole tools.
[0005] Conventionally, downhole tools are landed and set at
specific predetermined locations by relying on the interaction
between the tool and a restriction or "no-go shoulder" of reduced
cross-section in the well bore in the form of a landing or locating
nipple. Typically the no-go shoulder provides a surface that
restricts further downward passage of the tool. Force can then be
applied to the tool to actuate the latch dogs and set the tool at a
predetermined location along the length of the well bore.
Alternatively, downhole tools and measuring devices are run into
the bore of a well and landed in a so-called "side pocket mandrel"
which has been installed as part of the drillpipe or tubing string
when the well was cased. A side pocket mandrel typically has a main
bore aligned with the bore of the drillpipe and a receptacle bore
laterally offset from the main bore and extending alongside
thereof. The receptacle bore typically has an electrical contact or
prong in one end which is electrically connected to suitable
equipment at the surface. Side pocket mandrels can be used for
locating measuring devices used to monitor parameters such as
downhole pressure and temperature whilst allowing other downhole
tools to be lowered into the well. Side pocket mandrels are 99%
used for gas injection or chemical injection. A retrievable valve
is located in the side pocket which controls the flow of chemical
or gas from the annulus to the production tubing.
[0006] Examples of downhole tools which are actuated by interaction
with a restriction in a cased well bore are described in U.S. Pat.
No. 4,823,872 (Hopmann) and AU703766 (McLeod). Examples of running
tools which are used to position a tool in a side pocket mandrel
are described in GB 2170247 (Schnatzmeyer) and U.S. Pat. No.
2,962,097 (Dollison).
[0007] Typically a running tool is used to land and set other
downhole tools in a well. Once set, the downhole tool may be left
in place for several hours or several days, while the running tool
is retrieved to the surface. In recent times, running tools and
downhole tools have been designed to be lowered, manipulated and
retrieved using a conventional single or multi-strand electric
cable known as `wire line` or a single strand non-electric cable
known as `slickline`.
[0008] Using traditional tools, it only possible to set the tools
at the pre-determined locations where a landing nipple or side
pocket mandrel has been pre-installed. The locations of the side
pocket mandrels and landing nipples are fixed at the time when the
well is designed and installed and add to the cost of designing the
well. Moreover, in order to provide a plurality of landing nipples,
the internal diameter of the casing becomes progressively narrower,
making it increasingly difficult to accommodate and manipulate
downhole equipment. Any restriction in the diameter of, in
particular, a lower section of a well bore makes operation of the
well more difficult and may lead to a significant loss of potential
production from the reservoir. This loss of production is due to a
pressure drop created across each well bore restriction. The
smaller the restriction the greater the drop in pressure and the
greater the drop in production rate as a result.
[0009] One type of downhole tool that may be landed, set and
retrieved in a well bore is a bridge plug. A bridge plug is a
device that is set across the bore of a cased well to test the
pressure integrity of, isolate, or seal a section of the well bore.
Bridge plugs may also be used to straddle a section of a cased well
that has been perforated to flow test a formation. The bridge plug
may be set as a permanent measure or be retrievable.
[0010] To perform the function of a bridge plug, the downhole tool
must be able to be anchored in its set position in the well bore
and form a seal to isolate a section of a cased well bore.
Traditionally, bridge plugs are provided with an anchoring means on
the plug itself arranged to engage at any depth within a given
tubing internal diameter. Conventional bridge plugs require
considerable force to be used to set the plug and to provide the
necessary seal between the plug and the internal diameter of the
cased well bore. This force is traditionally provided using
explosive charges.
[0011] An alternative to traditional bridge downhole tools is
described in U.S. Pat. No. 5,366,010 (Zwart). Zwart describes a
retrievable bridge plug and running tool which can be set using
wireline or slickline. The bridge plug of Zwart is provided with
upper and lower sets of toothed locking slips which are movable
into a radially extended bore wall engaging position by application
of a downward force to a central sleeve along which an upper and
lower member are axially slidable. After setting of the upper and
lower slips, the bridge downhole tool of Zwart is brought into
sealing engagement with the bore wall by application of an upward
force to the lower member to compress a sealing means located
between the upper and lower slips.
[0012] The Zwart design has several problems. The complex
arrangement of nested sleeves results in a concomitant reduction in
the internal diameter of the downhole tool itself. This makes it
difficult to accommodate the passage of other downhole equipment
through the hollow bore of the Zwart bridge plug to a lower level.
The reduced bore of the Zwart bridge plug also restricts production
flow through the internal diameter of the set bridge plug. The
setting and retrieval operations of the Zwart bridge plug are quite
complex, the Zwart bridge plug being provided with a large number
of shear pins each of which control relative axial movement of a
series of nested sleeves, the setting and retrieval operations
requiring a complex series of upward and downward forces to be
applied in a particular sequence to shear the pins in a particular
order. Given that bridge plugs can be deployed at large depths down
a well bore, it can be extremely difficult for a operator at the
surface to determine whether or not the setting or retrieval
operation is progressing as required when using the Zwart bridge
plug.
[0013] The present invention was developed to provide an
alternative settable retrievable downhole tool that can be located
at any depth within a well bore without needing an interaction
between the well tool and a restriction or recesses within the well
bore to land, set or retrieve the downhole tool.
[0014] It will be clearly understood that, although prior art use
and publications are referred to herein, this reference does not
constitute an admission that any of these form a part of the common
general knowledge in the art in Australia or in any other
country.
[0015] In the statement of invention and description of the
invention which follow, except where the context requires otherwise
due to express language or necessary implication, the word
"comprise" or variations such as "comprises" or "comprising" is
used in an inclusive sense, i.e. to specify the presence of the
stated features but not to preclude the presence or addition of
further features in various embodiments of the invention.
SUMMARY OF THE INVENTION
[0016] According to a first aspect of the invention there is
provided a downhole tool retrievably settable within a suitably
sized cased well bore, the downhole tool comprising: [0017] a
mandrel; [0018] a downhole tool anchoring means mounted on the
mandrel and reconfigurable from a retracted configuration to permit
movement of the downhole tool through the well bore to a radially
expanded configuration for releasably engaging the cased well bore,
the downhole tool anchoring means being biased towards the
retracted configuration; [0019] a downhole tool setting means for
resisting movement of the tool anchoring means from the expanded
configuration back to the retracted configuration until a release
mechanism is released to allow retraction of the downhole tool
anchoring means and retrieval of the downhole tool from the well
bore; and, [0020] one or more locking means for locking the
downhole tool anchoring means in the retracted configuration after
the release mechanism has been released.
[0021] In one embodiment, the downhole anchoring means is
reconfigured from the retracted configuration to the radially
expanded configuration upon application of an axial force.
Preferably, the downhole anchoring means is a set of bi-directional
slips.
[0022] In one embodiment the downhole tool setting means is a
ratchet.
[0023] Preferably, the release means is arranged for engagement
with a fishing tool and operable thereby to permit release of the
downhole tool setting means allowing the downhole tool anchoring
means to retract into the retracted configuration for retrieval of
the downhole tool.
[0024] In one embodiment, the downhole tool further comprises a
sealing means for providing a fluid seal between the downhole tool
and the well bore such that the downhole tool operates as a plug.
Preferably, the sealing means is controllably reconfigurable from a
retracted configuration to permit movement of the downhole tool
through a well bore and a radially expanded configuration for
sealing engagement with the bore wall. More preferably, the sealing
means is expanded into sealing engagement with the bore wall by
applying a repeated compressive force to the sealing means after
the downhole tool anchoring means has been expanded into engagement
with the well bore.
[0025] Advantageously the downhole tool anchoring means are
positioned below the downhole tool sealing means so that debris may
not fall below the sealing means and foul the downhole tool
anchoring means. When the downhole tool is provided with a sealing
means, the downhole tool may further comprises a pressure
equalisation means for equalising any pressure differential that
may exist across the downhole tool prior to retrieval.
[0026] The downhole tool may further comprise a downhole tool
setting release means releasable from a locked configuration in
which expansion of the downhole tool sealing and/or anchoring means
is prevented to a released configuration in which expansion of the
downhole tool sealing and/or anchoring means is permitted.
Preferably, the downhole tool setting means is in the form of one
or more shear pins, shear screws or snap rings.
[0027] The downhole tool may be used in combination with a running
tool for landing and reconfiguring the tool in the well, the
downhole tool being releasably coupled to the running tool.
[0028] In an alternative embodiment, the downhole tool further
comprises a measuring device for monitoring one or more well
parameters. Preferably the measuring device is suspended from the
downhole tool and the mandrel of the downhole tool is hollow to
permit the flow of fluids therethrough.
[0029] According to a second aspect of the present invention there
is provided a running tool for landing and setting a retrievable
downhole tool at any location in a well bore, the running tool
comprising: [0030] an inner rod; [0031] a running tool anchoring
means mounted on the inner rod and controllably reconfigurable
between a retracted configuration to permit movement of the tool
through the well bore and a radially extended configuration for
locking engagement of the running tool with the bore wall; [0032] a
running tool actuating assembly for effecting reciprocal movement
of the reconfiguring the running tool anchoring means to and from
the retracted and expanded configurations without interacting with
any restrictions or recesses within the well bore; the tool
actuating assembly being moveable from a first configuration in
which the tool anchoring means is retracted and a second
configuration in which the tool anchoring means is expanded in
response to the application of an axial force; and, [0033] a
resistance means for frictionally engaging the bore wall with
sufficient gripping force so as to hold the position of the running
tool relative to the well bore during movement of the running tool
actuating assembly to and from the first and second configuration
upon application of the axial force.
[0034] Preferably the running tool anchoring means is in the form
of a set of slips cooperating with at lease one expansion cone,
each slips provided with a plurality of teeth directed to resist
downward movement of the running tool when the running tool
anchoring means is in the expanded configuration. Advantageously,
the resistance means has a fixed end and an axially slidable end to
accommodate movement of the running tool past any restrictions in
the well bore during setting and/or retrieval of the running tool.
In one embodiment, the resistance means is one ore more bow
springs.
[0035] To assist in retrieval of the running tool, the running tool
anchoring means may be biased towards the retracted
configuration.
[0036] Preferably, the running tool actuating assembly is a J-slot
mechanism comprising an actuating pin receivable in a J-slot
profile, the J-slot profile having one ore more short legs and one
ore more long legs, the actuating pin being constrained to move
between a short leg and a long leg upon application of an axial
pulling force to the tool actuating assembly, whereby when the
actuating pin is located in one of the short legs the tool
anchoring assembly is in the first configuration and when the
actuating pin is located in one of the long legs the tool anchoring
assembly is in the second configuration. Alternatively, the running
tool actuating assembly comprises a J-slot mechanism comprising an
actuating pin receivable in a J-slot profile, the J-slot profile
having one ore more short legs and one ore more long legs, the
actuating pin being constrained to move between a long leg and a
short leg upon application of an axial pushing force to the tool
actuating assembly, whereby when the actuating pin is located in
one of the long legs the tool anchoring assembly is in the first
configuration and when the actuating pin is located in one of the
short legs the tool anchoring assembly is in the second
configuration.
[0037] According to a third aspect of the present invention there
is provided a downhole tool/running tool system for retrievably
setting the downhole tool at any location within a well bore, the
system comprising: [0038] a running tool comprising an inner rod, a
running tool anchoring means mounted on the inner rod and
controllably reconfigurable between a retracted configuration to
permit movement of the tool through the well bore and a radially
extended configuration for locking engagement of the running tool
with the bore wall, a running tool actuating assembly for effecting
reciprocal movement of the reconfiguring the running tool anchoring
means to and from the retracted and expanded configurations without
interacting with any restrictions or recesses within the well bore,
the tool actuating assembly being moveable from a first
configuration in which the tool anchoring means is retracted and a
second configuration in which the tool anchoring means is expanded
in response to the application of an axial force, and, a resistance
means for frictionally engaging the bore wall with sufficient
gripping force so as to hold the position of the running tool
relative to the well bore during movement of the running tool
actuating assembly to and from the first and second configuration
upon application of the axial force; [0039] a downhole tool
comprising a mandrel, a downhole tool anchoring means mounted on
the mandrel and reconfigurable from a retracted configuration to
permit movement of the downhole tool through the well bore to a
radially expanded configuration for releasably engaging the cased
well bore, the downhole tool anchoring means being biased towards
the retracted configuration, and, a downhole tool setting means for
resisting movement of the tool anchoring means from the expanded
configuration back to the retracted configuration until a release
mechanism is released to allow retraction of the downhole tool
anchoring means and retrieval of the downhole tool from the well
bore; and, [0040] means for releasably coupling the downhole tool
with the running tool, said means facilitating transfer of axial
loads between the running tool and downhole tool during landing and
setting of the downhole tool in the well bore and arranged to
release the running tool from the downhole tool upon application of
an upward jarring force.
[0041] Preferably the means for releasably coupling the downhole
tool with the running tool includes one or more load transfer keys
axially moveable along a keyway in response to the application of
an axial force whereby an axial force applied to the running tool
is transmitted to the downhole tool.
[0042] In one embodiment, the downhole tool of the system further
comprises a downhole tool sealing means mounted on the mandrel and
moveable from a retracted configuration to permit movement of the
downhole tool through a well bore and a radially expanded
configuration for sealing engagement with the bore wall. In this
embodiment, the system may further comprise one or more seals in
combination with the sealing means for ensuring pressure integrity
across the downhole tool sealing means when the downhole tool
sealing means is in the radially expanded configuration.
[0043] In an alternative embodiment, the downhole tool/running tool
system further comprises a measuring device for monitoring one or
more well parameters.
[0044] According to a fourth aspect of the present invention there
is provided a method of setting a downhole tool in a bore, the
method comprising the steps of [0045] a) coupling the downhole tool
of claim 1 with the running tool of claim 16 so as to form a
running tool/downhole tool assembly; [0046] b) running the running
tool/downhole tool assembly into the bore of a well to any desired
location within the well bore, the running tool anchoring means and
the downhole tool anchoring means being in their respective
retracted configurations; [0047] c) applying an axial force in a
first direction to the running tool so as to reconfigure the
running tool anchoring assembly into the expanded configuration;
[0048] d) thereafter applying an axial force in a second direction
to reconfigure the downhole tool anchoring assembly into the
expanded configuration in engagement with the bore wall so as to
set the position of the downhole tool within the well bore; and
[0049] e) thereafter releasing the running tool from the downhole
tool for retrieval of the running tool from the well bore.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] In order to facilitate a more comprehensive understanding of
the nature of the invention, embodiments of the downhole tools in
accordance with the various aspects of the invention will now be
described in detail, by way of example only, with reference to the
accompanying drawings, in which:
[0051] FIG. 1 is split into three portions for the interest of
clarity and provides a half-sectional view of a first embodiment of
a running tool and bridge plug assembly shown in a configuration
suitable for running the assembly into a well bore;
[0052] FIG. 2 is split into three portions for the interest of
clarity and provides a half-sectional view of the running tool and
bridge plug assembly of FIG. 1 shown in a configuration suitable
for landing the assembly in the well bore;
[0053] FIG. 3 is split into three portions for the interest of
clarity and provides a half-sectional view of the running tool and
bridge plug assembly of FIG. 1 shown in a configuration suitable
for setting the bridge plug anchoring and sealing means in the well
bore;
[0054] FIG. 4 is split into two portions for the interest of
clarity and provides a half-sectional view of the running tool and
bridge plug assembly of FIG. 1 shown in a configuration suitable
for retrieval of the running tool from its set position in the well
bore;
[0055] FIG. 5 is split into two portions for the interest of
clarity and provides a half-sectional view of the bridge plug of
FIG. 1 shown in its set configuration in the well bore;
[0056] FIG. 6 is split into two portions for the interest of
clarity and provides a half-sectional view of a fishing tool being
used to retrieve the set bridge plug of FIG. 5 from the well
bore;
[0057] FIG. 7 is split into three portions for the interest of
clarity and provides a half-sectional view of a second embodiment
of a running tool and downhole tool assembly shown in a
configuration suitable for running the assembly into a well
bore;
[0058] FIG. 8 is split into three portions for the interest of
clarity and provides a half-sectional view of the running tool and
downhole tool assembly of FIG. 7 shown in a configuration suitable
for landing the assembly in the well bore;
[0059] FIG. 9 is split into three portions for the interest of
clarity and provides a half-sectional view of the running tool and
downhole tool assembly of FIG. 7 shown in a configuration suitable
for setting the downhole tool anchoring means in the well bore;
[0060] FIG. 10 is split into two portions for the interest of
clarity and provides a half-sectional view of the running tool and
downhole tool assembly of FIG. 7 shown in a configuration suitable
for retrieval of the running tool from its set position in the well
bore;
[0061] FIG. 11 is split into two portions for the interest of
clarity and provides a half-sectional view of the downhole tool of
FIG. 7 shown in its set configuration in the well bore;
[0062] FIG. 12 is split into two portions for the interest of
clarity and provides a half-sectional view of a fishing tool being
used to retrieve the set downhole tool of FIG. 11 from the well
bore; and,
[0063] FIG. 13 is a view of a downhole tools set in a well bore
with a measuring device suspended from the lowermost end of the
downhole tool for monitoring one or more well parameters.
DETAILED DESCRIPTION
[0064] Before the preferred embodiments of the present tools are
described, it is to be understood that the present invention is not
limited to the particular types of anchoring, setting and/or
sealing means described. It is also to be understood that the
terminology used herein is for the purpose of describing particular
embodiments only, and is not intended to limit the scope of the
present invention. Unless defined otherwise, all technical and
scientific terms used herein have the same meanings as commonly
understood by one of ordinary skill in the art to which this
invention belongs.
[0065] Throughout this specification reference is made to the tools
being set in a "well bore". The term "well bore" refers to a cased
well lined with one or more strings of drillpipe or tubing. Thus,
reference to engagement of a component with the well bore refers to
engagement of the component with the internal diameter of the
tubular used to line and/or case the well bore.
[0066] The term "downhole tool" is used to describe a tool that is
set in position in the well bore and remains in place for a period
of time. The term "running tool" is used to describe a tool that is
used to run, land or anchor, and set the downhole tool in the well
bore, the running tool then being retrieved to the surface.
[0067] The present invention is particularly suited for use in a
"monobore" well which is a well bore for which the internal
diameter remains substantially constant along its length. This type
of well bore completion string is the cheapest type and being able
to use a monobore well obviates the need to anticipate the location
of shoulders and keys for landing prior art type downhole tools or
instruments. It is considered that a person skilled in the art to
which the present invention belongs will appreciate that the size
of the outer diameter of the tool(s) will need to be selected to
match the internal diameter of the well bore in such a way that the
tool(s) can pass through the well bore to reach a desired location
in the well when the anchoring and/or sealing means described below
are in their respective retracted configurations and that the
anchoring and/or sealing means are able to be brought into
engagement with the internal diameter of the well bore when
configured into their respective expanded configuration. Thus,
selecting the correct size of tool(s) required for a given well
design is considered to be a matter of routine.
[0068] It is to be clearly understood that the present invention is
equally applicable to sub-sea, land wells, and platform wells for
oil and gas production as well as water injection and production
wells and wells used for waste disposal. In the interest of
clarity, the illustrations have been split into a plurality of
sections. Preferred embodiments are now described in detail with
reference to a downhole tool being releasably coupled with a
running tool to form a running tool/downhole tool system. In the
first described embodiment illustrated in FIGS. 1 to 12, the
downhole tool is provided with a sealing means so as to perform the
function of a bridge plug. In FIG. 13, the downhole tool does not
include a sealing means but rather is fitted with a measuring
device for monitoring one or more well parameters such as downhole
pressure, temperature, flow rates or the like. In this embodiment,
fluids such as hydrocarbons, oil, gas or water can flow through and
around the set downhole tool.
[0069] Referring to FIGS. 1 to 6, in the first described
embodiment, a retrievable downhole tool 10 in the form of a bridge
plug is releasably coupled to a running tool 12 so as to form a
downhole tool assembly. In each of these figures the uppermost ends
of the bridge plug 10 and running tool 12 are shown towards the
left-hand upper edge of each of the drawing sheets.
[0070] In FIG. 1, the bridge plug 10 and running tool 12 are each
shown in a retracted configuration suitable for running the
assembly downhole. The running tool 12 has an upper end 14 fitted
with a collar 16 referred to in the art as a `top sub` and a lower
end fitted with a bottom sub 20. The top sub 16 is provide for
attachment of wireline, slickline or coiled tubing (not shown) to
the upper end 14 of the running tool 12. The wireline, slickline or
coiled tubing is used to manipulate the running tool 12 to set the
position of the bridge plug 10 in the well bore.
[0071] The top sub 16 and lower sub 20 are each mechanically
coupled to an inner rod 18 which extends co-axially along the
length of the running tool 12 between the top sub 16 and a lower
sub 20. The lower sub 20 is contained within a slotted sub 21 which
is releasably coupled to the bridge plug 10 as described in greater
detail below.
[0072] The running tool 12 is provided with a running tool
anchoring means 22 in the form of a set of toothed slips mounted on
the inner rod 18 and reconfigurable between a retracted
configuration shown in FIG. 1 to permit movement of the running
tool 12 through the well bore and a radially extended configuration
for locking engagement of the running tool with the bore wall as
shown in FIG. 2. When the running tool slips 22 is in its radially
extended configuration, as illustrated in FIG. 2, the weight of the
running tool 12 and bridge plug 10 is suspended from the expanded
running tool slips 22.
[0073] When the running tool slips 22 are in the retracted
configuration shown in FIG. 1, the external diameter of the running
tool 12 is less than the internal diameter of the well bore. The
running tool slips 22 are biased towards this retracted
configuration using biasing means 23 in the form of flat springs
23. The running tool slips 22 are held on the J-mandrel by means of
a slips retaining sleeve 25. Expansion of the running tool slips 22
into the expanded configuration of FIG. 2 occurs by causing axial
movement of the running tool slips 22 towards a slips expansion
cone 26. The frustoconical shape of the slips expansion cone 26
forces radial outward movement of the running tool slips 22 into
its extended configuration thereby bringing the running tool slips
22 into locking engagement with the bore wall.
[0074] Movement of the running tool slips 22 relative to the slips
expansion cone is controlled by reconfiguring a running tool anchor
actuating assembly 19 from a first configuration in which the
running tool slips 22 are spaced apart from the slips expansion
cone 26 and thus retracted as shown in FIG. 1, and a second
configuration in which the running tool slips 22 are moved towards
the slips expansion cone 26 and are thereby expanded as shown in
FIG. 2.
[0075] Reconfiguration of the running tool anchor actuating
assembly 19 between the first and second configurations is achieved
by the application of an upward pulling force to the running tool
12 using a wireline (not shown) attached to the top sub 16.
Repeated application of an upward axial pulling force and downward
movement causes the running tool anchor actuating assembly 19 to
repeatedly switch between the first and second configurations in a
controlled manner as described below.
[0076] In the illustrated examples, the running tool anchor
actuating assembly 19 is provided in the form of a continuous
J-slot mechanism comprising an actuating cam or pin 36 which is
caused to travel along a continuous J-slot profile 29 machined into
a J-slot mandrel 30 coaxial with the inner rod 18. The actuating
pin 36 extends outwardly from a J-pin bearing 38 which is mounted
on and rotatable about the J-slot mandrel 30 and retained thereon
by a J-pin bearing retaining means 39.
[0077] The J-slot profile 29 (best seen in FIG. 2) has a continuous
alternating series of long legs 32 and short legs 34, the
particular sequence of long and short legs not being critical to
the working of the present invention provided only that legs of
differing length are provided within the J-slot profile 29. The
J-slot mechanism 28 may equally have the actuating pin 36 extending
from the J-slot mandrel 30 with the J-slot profile 29 being
provided in a sleeve or sleeves (not shown) co-axially mounted on
the J-slot mandrel 30 and able to rotate about the inner rod 18.
The J-slot mechanism could also equally be reversed such that an
axial pushing force would be required to move the actuating pin
from one of the long legs to one of the short legs, thereby moving
the running tool actuating assembly from the first configuration to
the second configuration.
[0078] Using the illustrated example, when the actuating pin 36 is
positioned in one of the short legs 34 of the continuous J-slot
profile 29, the running tool anchor actuating assembly 19 is locked
in its first configuration and the running tool slips 22 are
retracted to allow passage of the running tool 12 through the well
bore. When the actuating pin 36 is moved such that it is located
within one of the long legs 36 of the continuous J-slot profile 29,
the running tool anchor actuating assembly 19 is in its second
configuration in which the running tool slips 22 are expanded into
locking engagement with the internal diameter of the cased well
bore. The relative length of the long and short legs 32 and 34,
respectively, are chosen according to the relative displacement of
the running tool slips 22 from the expansion cone 26 in such a way
that the running tool slips 22 are spaced apart from the slips
expansion cone 26 when the actuating pin 36 is located in one of
the short legs 34 and the running tool slips 22 are expanded onto
the slips expansion cone 26 when the actuating pin is located
within one of the long legs 32.
[0079] The running tool 12 of the present invention is able to be
landed and anchored at any depth within a suitably sized well bore
without the need to interact with any recesses or restrictions
provided within the well bore. To provide the reaction force
required to manipulate the running tool anchor actuating assembly
19 by wireline, the running tool 12 is provided with a resistance
means 24. The resistance means 24 frictionally engages the bore
wall with sufficient gripping force so as to hold the position of
the running tool relative the bore wall when the axial pulling
force is applied to actuate the running tool anchor actuating
assembly 19. In the illustrated example, the resistance means 24
comprises a set of three radially spaced and axially oriented bow
springs located at 120.degree. separation relative to each other
around the circumference of the running tool 12. The resistance
means may equally take the form of one or more spring loaded drag
block(s) or any other number of bow springs, provided only that the
resistance means 24 is capable of generating sufficient gripping
force to counterbalance the axial force used to reconfigure the
running tool anchor actuating assembly 19. The amount of frictional
drag between the bow springs 24 and the internal diameter of the
cased well bore may be adjusted by addition of a coil spring and an
adjustable threaded spring compression device (not shown). In this
example, one end of the bow springs 24 is fixed whilst the other is
provided with a floating ring 27 retained by a bow spring sleeve 29
which is coaxially mounted on and axially slidable relative to the
J-mandrel 30. The floating ring 27 allows compression of the bow
springs 24 as the running tool passes through any restrictions in
the well bore during running and/or retrieval operations.
[0080] In use, to running tool 12 is provided in its retracted
configuration with the running tool anchor actuating assembly 19 in
its first configuration, and run into the well bore to any desired
depth. The actuating pin 36 is located in one of the short legs 34
of the J-slot profile 29. On reaching a desired location in the
well, the tool anchor actuating assembly 19 is moved into its
second configuration in which the actuating pin is located in one
of the long legs 36 by applying an upward pulling force through a
wireline (not shown) attached to the top sub 16 to move the
actuating pin 36 out of one of the short legs 34. Subsequent
release of the upward pulling force caused the actuating pin 36 to
track across the J-slot profile 29 into one of the long legs 32
thereby moving the running tool anchor actuating assembly 19 into
its second configuration. The bow springs 24 of the running tool 12
provide sufficient gripping force to hold the running tool 12 in
position while the running tool anchor actuating assembly 19 is
being reconfigured. When the running tool anchor actuating assembly
19 is in its second configuration, the running tool slips 22 have
been brought into locking engagement with the bore wall.
[0081] The running tool slips 22 comprise a set of three
replaceable steel wedges that, in the extended configuration,
together form a near-circle around the well bore. The replaceable
steel wedges are provided with hardened teeth that embed slightly
into the bore wall. Application of further downward force to the
running tool 12 assists in increasing the biting force applied,
fixing the running tool more securely in position in the bore wall.
The teeth of the running tool slips 22 are angled for locking
engagement of the running tool slips 22 with the bore wall in one
direction only, namely downwardly, to allow ease of retrieval of
the running tool 12. It is to be understood, however, that the
teeth of the running tool slips 22 could equally be angled
bi-directionally if desired.
[0082] With reference to FIG. 3, release of the running tool slips
22 from the expanded configuration is achieved by application of a
second upward pulling force so as to cause the actuating pin 36 to
move out of one of the long slots 32 of the J-slot profile 29. When
this pulling force is released, the actuating pin 36 tracks across
the J-slot profile 29 and become located in one of the short slots
34. This causes the running tool slips 22 to return to the
retracted configuration which is assisted by the bias force of flat
springs 23. This feature allows the position of the running tool
within the well bore to be adjusted if it is found that the
assembly has not been positioned at the correct depth on the first
attempt. Moreover, by making the J-slot profile 29 continuous,
repeated indexing can be used if required, for example if
difficulties such as jamming occurs during the landing or setting
operations.
[0083] Once the running tool slips 22 are locked in engagement with
the bore wall, further downward movement of the running tool 12 and
downhole tool 10 relative to the well bore is prevented.
[0084] The running tool 12 is releasably coupled to the bridge plug
10 by a release mechanism that allows the transfer of axial force
from the set running tool 12 to the bridge plug 10.
[0085] The running tool 12 is further provided with a set of load
transfer keys 40 constrained to move axially downwardly along a
keyway 41 provided in the slotted sub 21. The load transfer keys 40
are retained in position using a key retainer sleeve 42 coaxially
mounted on the slotted sub 21, the key retainer sleeve being
mechanically coupled with a lower outer sleeve 44 positioned at the
lowermost end of the running tool 12.
[0086] At its upper end 52, the bridge plug 10 is provided with an
external or internal fishing neck 50 coaxially mounted on an upper
inner mandrel 56 of the bridge plug 10. The fishing neck 50 is
shaped to be engageable with a correspondingly shaped fishing tool
(described in greater detail below with reference to FIG. 6) to
facilitate retrieval of the bridge plug 10 after it is set. The
fishing neck 50 is capable of axial movement relative to the upper
inner mandrel 56 in one direction only, the fishing neck 50 being
releasably coupled to the upper inner mandrel using a ratchet
mechanism 61 described in greater detail below. Application of a
downward axial force to fishing neck 50 causes it to move
downwardly relative to the upper inner mandrel 56.
[0087] When the running tool 12 and bridge plug 10 are coupled to
form the assembly that is run into the well bore, a lower bearing
surface 46 of the lower outer sleeve 44 is brought into abutting
contact with an upper bearing surface 48 of the fishing neck 50. In
order to set the position of the bridge plug 10, a downward jarring
force is applied to the running tool 12, causing the load transfer
keys 40 to move downwardly along the keyway 41. This downward force
is transferred to the bridge plug 10 across the abutting surfaces
46 and 48. The downward jarring force is preferably applied using a
jarring tool used on a slickline, wireline or coiled tubing tool
string (not shown). The jarring tool may be hydraulic or mechanical
provided only that it is able to apply a repeated axial jarring
force through the running tool 12 to the downhole tool 10.
[0088] Movement of the fishing neck 50 relative to the upper inner
mandrel 56 during the running operation is prevented by releasably
coupling the fishing neck 50 to the upper inner mandrel using one
or more downhole tool setting shear screws 58. When the downward
jarring force is applied, sufficient force must first be applied to
shear the downhole tool setting shear screws 58 to allow downward
movement of the fishing neck 50 relative to the upper inner mandrel
56.
[0089] The bridge plug 10 is further provided with a downhole tool
anchoring means 74 mounted on a mid inner mandrel 45. The mid inner
mandrel 45 is positioned below the upper inner mandrel 56 and
threadedly connected thereto. The downhole tool anchoring means 74
is controllably reconfigurable from a retracted configuration shown
in FIG. 1 to permit movement of the downhole tool 10 through the
well bore to a radially expanded configuration shown in FIG. 3 for
releasably engaging the cased well bore. The downhole tool
anchoring means 74 is biased towards the retracted configuration
using a biasing means 75 in the form of one or more garter
springs.
[0090] In the illustrated embodiments, the downhole tool anchoring
means 74 is in the form of a set of interconnected upper and lower
downhole tool slips 81 and 83, respectively. The set of upper and
lower downhole tool slips 81 and 83 operates in a similar fashion
to that described above with reference to the running tool slips
22. The main difference between the downhole tool anchoring means
74 and the running tool anchoring means 22 is the way in which the
slips are actuated into the expanded configuration.
[0091] Expansion of the upper slips 81 is facilitated by allowing
axial movement of an upper slips cone 76 towards the upper slips
81. At the same time, the interconnected lower slips 83 which are
in a fixed spaced apart arrangement with the upper slips 81 extend
radially outwardly by running up the frustoconical outer surface of
a lower slips cone 78. Expansion of the downhole tool anchoring
means 74 is prevented whilst the assembly is being run into the
well bore and until after the running tool has been landed and
anchored by the presence of the downhole tool setting shear screws
72.
[0092] After shearing of the downhole tool setting shear screws 58,
further downward jarring causes further downward travel of the
fishing neck 50 relative to the upper inner mandrel 56 to compress
a sealing means 60 mounted on the inner mandrel 45. In the
illustrated embodiment of FIG. 3, the sealing means 60 is in the
form of a resiliently compressible elastomeric packing element.
Other suitable sealing means may equally be employed provided only
that the sealing means is capable of sealing engagement with the
internal diameter of a well bore upon application of a downwardly
applied force. The sealing means 60 has a retracted or collapsed
configuration in which the outside diameter of the sealing means is
smaller than the internal diameter of the well bore, as illustrated
in FIG. 1, and a radially expanded configuration for sealing
engagement with the bore wall, as illustrated in FIG. 3.
[0093] To prevent retraction of the expanded elastomeric packing
element 60 between successive jars, the bridge plug 10 is provided
with a downhole tool setting means in the form of a ratchet 61
which allows axial downward axial movement of the fishing neck 50
relative to the upper inner mandrel 56 to cause expansion of the
elastomeric packing element 60 and downhole tool anchoring means
74, whilst concomitantly resisting upward movement of the fishing
neck 50 relative to the upper inner mandrel 56. The ratchet 61
comprises a ratchet ring 62 in toothed engagement with a matching
ratchet sleeve 64. The ratchet ring 62 is mechanically coupled with
a portion of the fishing neck 50. The ratchet sleeve 64 is mounted
on the upper inner mandrel 56. In order to facilitate subsequent
retrieval of the downhole tool 10 after it has been set, the
ratchet 61 includes a shearable release mechanism described in
greater detail below.
[0094] The downhole tool is further provided with a relaxation
buffer spring 70 housed in a spring housing 71 mounted on the mid
inner mandrel 45. During use of the downhole tool in the well,
movement of the elastomeric packing element 60 may occur due to
relaxation of the elastomeric material over time. This could cause
a relaxation of the force being applied to the downhole tool slips
74 by upper and lower cones 76 and 78 respectively. The relaxation
buffer spring 70 is included in the design of the preferred
embodiment of the present invention to assist in retaining the
force applied to upper cone 76 in the event that the elastomeric
packing element 60 relaxes.
[0095] During the setting of the sealing means 60, the downhole
tool anchoring means 74 is maintained in the retracted
configuration. This is achieved by preventing axial movement of the
upper cone 76 relative to the mid inner mandrel 45 until a downhole
tool slips release shear screw 72 (best seen in FIG. 2) is sheared.
Shearing occurs when the energy stored in the elastomeric packing
element 60 and relaxation buffer spring 70 eventually exceeds the
shear rating of the downhole tool slips release shear screw 72.
[0096] Thereafter, further downward jarring force applied by the
jarring tool to the upper end 14 of the running tool 12 causes
downward axial movement of the upper cone 76 towards the upper
slips 81 expanding the downhole tool anchoring means 74 radially
outwardly into locking engagement with the bore wall. As the upper
slips 81 extends, so does the lower slips 83 which is fixed
thereto. The teeth of upper and lower slips 81 and 83 are oriented
to anchor the downhole tool 10 bi-directionally.
[0097] With the downhole tool anchoring means 74 in locking
engagement with the bore wall, the downhole tool is set. Further
downward jarring through the jar tool string may be applied to
ensure that the sealing means 60 is fully expanded in sealing
engagement with the bore wall. The ratchet 61 holds both the
sealing means 60 and downhole tool anchoring means 74 in their
respective expanded configurations.
[0098] Once the downhole tool 10 has been set, the running tool 12
may then be released from the downhole tool 10 and recovered to the
surface by applying an upward pulling force sufficient to cause
shearing of one ore more release shear pins 54 (best seen in FIG.
2). The release shear pins 54 are used to releasably couple the
slotted sub 21 of the running tool 12 with the upper inner mandrel
56 of the downhole tool 10. To ensure that the various shear screws
or shear pins used are sheared in the correct sequence, the tool
release shear pins 54 have a much higher shear rating than the
downhole tool setting shear screws 58.
[0099] Once the tool release shear pins 54 have been sheared,
further upward jarring causes retraction of the extended running
tool slips 22 into the retracted configuration by moving the
expansion cone 26 away from the running tool slips 22. The flat
springs 23 assist in the retraction of the running tool slips 22.
The floating ring 27 allows the bow springs 24 to collapse for
passage of the running tool past any restrictions in the well
bore.
[0100] During this pulling operation, the actuating pin 36 will
"fall" back down one of the long legs 32 of the J-slot profile 29
and then be positioned below the start of the next short leg 34
without actually entering the short leg 32 at this time. If a
downwards movement back into the well bore occurs during recovery,
the actuating pin 36 will locate within the short leg 34 preventing
the running tool slips 22 from expanding. This action allows the
downhole tool running tool to be able to move unhindered both out
and in the well bore.
[0101] FIG. 5 shows the configuration of the set downhole tool 10
after removal of the running tool 12.
[0102] It is to be understood that the design of the downhole tool
10 lends itself to deployment downhole by means other than
slickline wire, including but not limited to: electric line; coiled
tubing; or drilled pipe, which may not require the use of any
running tool. It is to be further understood that the anchoring
and/or sealing means of the downhole tool may equally be set
without the use of the running tool described above by using other
means to apply the jarring force, for example, a hydraulic pressure
delivered from the surface, a pyrotechnic setting device, a well
pressure activated setting device or an electromechanical setting
device. Thus, the present invention is not limited to the running
tool and downhole tool being used together. Similarly, the running
tool described above may be used independently of the downhole tool
to carry other downhole equipment such as a measuring device into
the well bore.
[0103] If it becomes necessary to retrieve the set downhole tool 10
from the well bore, the sealing means 60 and downhole tool
anchoring means 74 first needs to be reconfigured into the
retracted configuration illustrated in FIG. 6. This can only be
achieved by disengaging the ratchet 61 which is achieved by
releasing a release mechanism comprising one or more ratchet
release keys 66 retained by a key retaining sleeve 80 mounted
internally on the upper inner mandrel 56 of the downhole tool 10.
The key retaining sleeve 80 is held against axial movement by a
ratchet release shear screw 82 (best seen in FIG. 5).
[0104] With reference to FIG. 6, a fishing tool 90 is run into the
well, the fishing tool 90 being provided with a fishing head 92 for
engagement with the fishing neck 50 of the downhole tool 10. The
fishing tool 90 is further provided with a prong 93 for applying a
downward force to the key retaining sleeve 80. Sufficient downward
force is applied by the prong 93 to the key retaining sleeve 80 to
overcome the shear rating of the ratchet release shear screws 82.
When the ratchet release shear screws 82 shear, the key retaining
sleeve 80 is free to slide axially downwardly, causing the ratchet
release keys 66 to fall inwards. In this way, the ratchet 61 is
disengaged, allowing the ratchet sleeve 64 to slide upwardly to
release the energy stored in the expanded sealing means 60 and
relaxation buffer spring 70. Thereafter, further application of an
upward pulling force to the downhole tool causes further retraction
of the sealing means 60 and further relaxation of the relaxation
buffer spring 70.
[0105] In order to prevent re-expansion of the downhole tool
sealing means 60 during retrieval of the downhole tool 10, the
downhole tool 10 is further provided with a first positive locking
means 95 for locking the downhole tool sealing means in the
retracted configuration. In the illustrated example of FIG. 5, the
first positive locking means 95 comprises a first snap ring 94
locatable in a first groove 96 machined into the mid inner mandrel
45. The first positive locking means 95 is locked into position by
application of sufficient pulling force to the downhole tool 10
after release of the ratchet release keys 66, until the first snap
ring 94 becomes located in the first groove 96. Once locked, the
first positive locking means 95 prevents re-expansion of the
sealing means 60 and buffer spring 70 during retrieval.
[0106] Once the first positive locking means 95 has been locked,
the application of a downward force to fishing tool 90 may be used
if required to encourage retraction of the downhole tool anchoring
means 74, the downward force being transmitted through the mid
inner mandrel 45 to the lower cone 78. Downhole tool slips biasing
means 75 in the form of garter springs assist retraction of the
downhole tool anchoring means 74.
[0107] A second positive locking means 101 in the form of a second
snap ring 100 and a second groove 102 provided in the mid inner
mandrel 45 to lock the downhole tool anchoring means 74 in the
retracted configuration during retrieval of the downhole tool. The
second snap ring 100 is caused to become located in the second
groove 102 upon application of an upward pulling force to the
downhole tool 10. The second locking means 101 locks the upper cone
76 to the mid-inner mandrel 45 when the second snap ring 100
becomes located in the second groove 102 as illustrated in FIG. 6.
The downhole tool 10 is further provided with a retrieval bias
means 104 in the form of a spring to assist in locating the second
snap ring 100 in the groove 102.
[0108] Without the second locking means 101 being provided, the
downhole tool anchoring means 74 may try to re-expand should any
part of the tool at or below the elastomeric packing element 60
become snagged whilst the bridge downhole tool 10 is being pulled
upwardly during retrieval. Alternatively, the sealing means 60
itself may fail due to circumferential rupture of the elastomeric
packing element, causing the elastomer to break into two separate
rings. This is a common source of failure of elastomeric packing
elements downhole. In this event, a lower section of the ruptured
elastomeric packing element 60 would be unrestrained and may swell,
depending on well conditions. A swollen section of a ruptured
elastomeric packing element 60 would be likely to catch in a well
during recovery of the bridge downhole tool 10. If this were to
occur, a compression force would be applied to the upper cone 76,
which may cause the downhole tool anchoring means 74 to re-expand
into engagement with the bore wall.
[0109] Prior to or during retrieval of the bridge downhole tool 10,
it is highly recommended that a check is undertaken to ensure that
no differential pressure exists across the bridge downhole tool 10
before the downhole tool anchoring means 74 are released. Failure
to do so may result in a sudden uncontrolled movement of the bridge
downhole tool 10 either up or down the tubing.
[0110] Pressure equalisation is typically achieved by means of
providing a pressure equalisation device (not shown) being
positioned on the downhole tool 10 towards a lowermost end of the
downhole tool below the sealing means 60.
[0111] A second embodiment of the present invention is illustrated
in FIGS. 7 to 12 for which like reference numerals refer to like
parts. The release mechanism between the running tool 12 and the
downhole tool 10 has been changed to provide an emergency release
feature. In this embodiment the slotted sub 21 is retained on the
J-mandrel 30 of the running tool and a retaining sleeve 140 in
abutting contact with fishing neck sleeve 42 is used to maintain a
close fit between running tool 10 and the downhole tool 12. An
extension piece 110 is threadedly engaged with the lowermost end of
the slotted sub 21, the extension piece being provided with a
failsafe release mechanism comprising a set of keys 120 which are
used to protect the shear screws 54 from experiencing any load
during the setting of the downhole tool anchoring means 74. If the
release shear screw 54 shears prematurely, there is a risk that the
downhole tool 10 could fall to the bottom of the well. The keys 120
are held in place between the internal diameter of the fishing neck
sleeve 50 and the outer diameter of the extension piece 110. A
collet 116 is mechanically coupled with the lower end of the
slotted sub 21 and coaxially mounted on the extension piece 110.
The collet 116 terminates at its lowermost end in a set of
expandable fingers 118 held in a radially expanded configuration by
an expanded head section 112 of the extension piece 110. The collet
fingers 118 are provided with an offset that engages with a
correspondingly shaped recess 132 in the uppermost end of the upper
inner mandrel 56 of the downhole tool 10.
[0112] During downward jarring, the keys 120 are retained in
position while the load transfer keys 40 are caused to travel along
keyway 41 thereby driving the fishing neck 50 downwardly relative
to the positions of the extension piece 110 and mid inner mandrel
56. As best seen in FIG. 9, when sufficient downward jarring has
been applied to reconfigure the downhole tool anchoring means 74
into the expanded configuration, the keys 120 are no longer
retained by the inner diameter of the fishing neck 50 and are
released outwardly into the cavity 114.
[0113] Once the keys 120 have been released into the cavity 114,
the release shear screws 54 are able to be sheared by the
application of an upward jarring force to release the running tool
12 from the set downhole tool 10 as described above. When the
release shear screws 54 shear, the extension piece 110 is released
to move upwardly relative to the collet 116. The expanded collet
fingers 115 are no longer held in the expanded configuration by the
head portion 112 of the extension piece 110. When the collet
fingers 115 retract, the lowermost ends 118 are released from the
recess provided in the uppermost end 132 of the mid inner mandrel
56, releasing the running tool 12 from the downhole tool 10.
[0114] Further modifications have been made to the downhole tool in
this embodiment. To provide pressure integrity against the flow of
fluids past the sealing means 60, an O-ring has been positioned
above the depth of the sealing means 60 and retained using an
O-ring seal support ring 125. An upper outer sleeve 67 has been
added to provide a cover for the downhole tool setting shear screws
58 with a retaining sleeve 130 holding the O-ring seal support ring
125 in place.
[0115] In each of the described embodiments, the downhole tool is
being used as a bridge plug and accordingly is provided with
expandable sealing means. The downhole tool could equally be used
for the setting of a measuring device for monitoring one or more
well parameters, the measuring device being attached typically to a
lowermost end of the downhole tool as shown in FIG. 13 for which
like reference numerals refer to like parts. In this embodiment,
the bore of the mid inner mandrel 45 of the downhole tool 12 is
hollow to allow for the passage of fluids such as hydrocarbons,
oil, gas or water through the bore of the downhole tool. The
downhole tool 12 in this illustrated example is not provided with a
sealing means 60 but is anchored into position within the well bore
using the downhole tool anchoring means 74 in the same ways as
described above. In place of the sealing means 60 the downhole tool
is optionally fitted with a vibration attenuation assembly 155
comprising at least one spring 153 retained on the mid inner
mandrel 45 by a spring housing 151, and a spring pusher 152. The
vibration attenuation assembly may be included to offset vibration
in the downhole tool due to the flow of fluids through and around
the downhole tool once set.
[0116] The lowermost end of the downhole tool 12 is fitted with a
measuring device suspension assembly 160 comprising a ported tool
suspension sub or gauge hanger 150 to which a measuring device 162
is coupled. The gauge hanger 150 is provided with one or more flow
ports 156 to permit the passage of fluids through the bore of the
mid inner mandrel 45 of the downhole tool 12.
[0117] Once set in the well, the measuring device may be used to
monitor or record data within the well while the well is flowing.
It should be noted that when the downhole tool is being used as a
bridge plug, flow of fluids through the bore of the inner mandrel
is prevented. The downhole tool of FIG. 13 is able to be retrieved
from the well bore in the same manner as described above in
relation to the first and second embodiment of the present
invention.
[0118] Now that the preferred embodiments and illustrative examples
of the present invention have been described in detail, the present
invention has a number of advantages over the prior art, including
the following: [0119] (a) the downhole tool can be landed at any
position within a known size of a cased well bore without needing
any interaction between the downhole tool or the running tool and
any restriction or recesses in the well to actuate either the
downhole tool or the running tool; [0120] (b) the downhole tool has
a larger internal diameter than other prior art devices, with the
complexity of the landing and anchoring means being moved from the
downhole tool to the running tool, which can then be used for
multiple downhole tools; [0121] (c) the downhole tool left downhole
also has the potential to be shorter than prior art devices which
is advantageous given that most wells have some degree of deviation
and tortuosity; [0122] (d) the setting of the downhole tool is less
complicated in that once the running tool has been anchored in
position by application of an upward force, thereafter only
downward forces are used to lock the downhole tool in position;
[0123] (e) the slips on the downhole tool are positioned below the
downhole tool sealing means which protects the slips from debris
that may fall down the well bore; [0124] (f) the use of the
positive locking means allows for the option of abandoning the
downhole tool to the bottom of the well if the downhole tool
becomes unable to be retrieved for any reason; and, [0125] (g) the
running tool itself does not have any shear screws or seals, which
makes it easier to strip down and re-use than the prior art running
tools used for prior art downhole tools.
[0126] Numerous variations and modifications will suggest
themselves to persons skilled in the relevant art, in addition to
those already described, without departing from the basic inventive
concepts. All such variations and modifications are to be
considered within the scope of the present invention, the nature of
which is to be determined from the foregoing description and the
appended claims.
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